Key words: valve; installation; use; maintenance 1 valve installation (1) before installation, check the appearance of the valve, without cracks, trachoma, mechanical damage.
(2) check to confirm the nameplate intact, and meet the requirements.
(3) clear the valve residue.
(4) Turn the valve stem to see if it is flexible and easy to install, so as to avoid invalid work. After the inspection is completed, clean the pipe connected to the valve, the available compressed air to blow away the pipe slag and other debris.
(5) Installation, should be strictly in accordance with the installation instructions provided by the manufacturer. When installing the threaded valve, seal packing should be wrapped around the pipe thread, to avoid the accumulation of the valve, affecting the flow of media. When installing the Flange valve, pay attention to the symmetrical tightening according to the specified torque so as to avoid uneven tightening torque and damage to the valve. Valve in the body direction signs, the valve should flow into and out of the correct direction of installation. For example, check valves , stop valves , throttle valves , pressure relief valve , if fitted anti-flip, will lose the valve in the piping system function, or even dangerous. Valve insulation installation. Where the transport medium prone to condensation in the ambient temperature caking phenomenon, should be combined with pipelines, with heat tracing, to prevent freezing valve.
(6) For the pipeline conveying flammable and explosive gases, the pipeline must be purged and replaced with nitrogen before the pipeline is put into production, to prevent the medium of transmission and the oxygen in pipeline from forming the explosion limit and avoiding the phenomenon of explosion occur.
2 valve maintenance (1) manual valve is the most widely used in the piping system valve. As a result of screw corrosion or valve internal hand wheel caused by foreign objects can not move, maintenance and repair measures should be taken so that the hand wheel can be flexible to move. Long lever is strictly prohibited to move. Otherwise easy to damage the internal sealing surface of the valve, or switch off the hand wheel, handle. Switch the valve, force to be smooth, to prevent uneven force caused damage to the valve seal packing. When the valve is fully open, the hand wheel should be rotated around a half or so, to avoid screw damage. Non-metallic valves, some hard and brittle, and some low intensity, the operation should be carried out slowly and steadily to prevent the valve cracks and other damage.
(2) In the pipeline system, the normally open valve may be closed due to the medium flowing in the valve, the valve sealing surface is stuck with debris, and the valve is closed to make it not close properly.
(3) In the piping system, normally open and normally closed valves should be checked according to the work environment and working conditions of the valve. First, the valve handwheel and screw rod should be inspected periodically to ensure safe and effective operation. The second is to periodically turn the hand wheel, add thread lubricant on the stem to prevent biting. Outdoor valves, to the stem plus protective sleeve to prevent rust pollution.
(4) the valve grease.
① Regular grease on the valve is to reduce valve sealing surface wear and improve valve life of the key measures. Valve sealing grease with a non-curing, non-dispersed, insoluble, good pressure resistance, sealing grease used in the valve model, the fat injection cycle, grease volume in accordance with the instructions provided by the manufacturer to carry out, in the working conditions of the more demanding occasions Lipid cycle may be appropriate in advance.
② Note the working position of the valve should be under normal circumstances, under normal circumstances, only the valve is fully open or fully closed position, the valve chamber can be isolated, otherwise the injected fat will flow into the pipe inside, can not play a corresponding role. For example, the Ball Valve grease should be in the fully open position, while the Gate Valve should be in the closed position. In other words, when the valve is injected, it is in the closed or fully open position, which is mainly determined by the structure of the valve itself. Therefore, before using the valve, carefully read the manuals provided by the manufacturer to avoid misoperation.
③ Note the first open when the body fat sewage valve drain plug pressure relief, and then clean the grease hole, in order to facilitate the smooth injection of fat. Note fat, the distance from the injection port after the advanced fat one after another, after the end of the grease, be sure to tighten the drain and drain plug. When the valve sealing system filled with grease, the pressure shows a slow change, the slower the better sealing effect. If you do not follow the law or not fat, that there is congestion, timely clearance. Pressure is too low, the seal is usually caused by failure of sealing grease leakage. The pressure is too high, usually the internal seal grease has hardened, or lipid channel blockage.
3 common faults and prevention (1) valve leakage is a common valve failure. Generally divided into two kinds of leakage and internal leakage, leakage in two ways: The first is the valve and pipeline contact site leakage, the second category is the valve itself cracks, rust or filler leakage. Internal leakage refers to the leakage caused by the lax valve closure.
(2) Leakage of valve and pipeline connection parts is usually caused by aging of gasket or loosening of connecting bolt. Such malfunction can open bypass pipe in time and replace gasket or fasten connecting bolt bolt according to work rules. For the valve body cracks, corrosion caused by leakage, repair costs and acquisition costs are relatively close to the valve, it is recommended to replace the new valve, do not have to take measures to repair the valve. There may be several reasons for the leakage caused by the packing. One is the corrosiveness of the packing and the working medium, and the incompatibility of temperature and pressure. At this time, the packing suitable for the working medium should be selected and reinstalled. Second, the filling method is wrong, resulting in leakage, this time should carefully read the valve manual, according to the correct method of filling. Third, the valve filler to use a longer time, aging caused by leakage, this time should be replaced by filler.
(3) lax valve leakage caused by the internal leakage, the following reasons are generally caused by ① first valve and valve stem loose connection, the stem has been to the next trip, but the valve disc and valve seat is not in close fit, this time should be According to the standard valve repair, fastening valve stem and the connection, thus eliminating the failure.
② The second is the valve stem bending and twisting, so that the valve can not even force, causing the seal is not strict; at this time should repair or replace the valve stem to eliminate the fault.
Is due to the pipeline medium containing impurities, attached to the valve seat or valve, the valve can not be closed. At this point should be timely maintenance, removal of impurities, troubleshooting.
③ The above is only the valve of the common failures and causes, the actual work, but also encounter other failures, to take the initiative to prevent the occurrence of valve failure, the most fundamental is to be familiar with the valve structure, working principle and the use of key points to achieve "Four understand three will" so that the use and maintenance of the valve to achieve economic security purposes.
4 Conclusion A wide range of valve varieties and specifications, are closely linked with our production and life an integral part of the valve installation, maintenance and repair methods to conduct research and description will help to engage in valve use and maintenance personnel.
references:
[1] JJG49-1999. Wang Yanfei editor. Valve installation, use and maintenance of the State Quality Supervision Bureau.
[2] JJG52-2002 editor Zhang Xiangying. Oilfield special project management. Engineering management of network oil field.
Flange-Quick Coupling Ball Valve,3PC Ss Ball Valves,Quick Coupling Ball Valve
Gaoshan Valve Co., Ltd. , http://www.hn-valves.com
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